Summary
When setting up a nominal discount promotion accumulating with more for less promotion, when there's a discount in the more for less only for 1 out of 2 items, leads to an incorrect discount on the 2nd order item due to the checkout split.
For instance, let's say there is a 50% discount only for 1 out of 2 items in a buy and win and then a -$300 off, with both promotions accumulating.
Let's say the item costs $200 and 2 are inserted.
The expected discounts would be:
Item (1) ---> -$100 + -$100 --> the 2nd items is only $100 because there is no additional "room" to be reduced from its price. Item (2) --> -$200 ---> the rest of the discount to compose the full -$300
However, the scenario that currently happens is:
Item (1) ---> -$100 + -$100 --> the 2nd items is only $100 because there is no additional "room" to be reduced from its price. Item (2) --> -$100 ---> the price of the 1st item, from the split is replicated
This only happens if the discounted items are 2+ units of the same SKU and the "combo" of promotions specified above.
Simulation
1 - create a percentual promotion 2 - create a buy and win promotion that gives discount for only the 2nd item 3 - insert 2 units of said item in the cart
OBS: the combination of prices and discounts must be in a way that the "amount to be discounted" from the price of the 1st item is not enough to compose 50%+ of the nominal discount value